docs: def init_sdr(self):
          """Initialize SDR
  
          Do the appropriate action to have a relevant sensor description
          repository for the current management controller
          """
          # For now, return current sdr if it exists and still connected
          # future, check SDR timestamp for continued relevance
          # further future, optionally support a cache directory/file
          # to store cached copies for given device id, product id, mfg id,
          # sdr timestamp, our data version revision, aux firmware revision,
          # and oem defined field
          if self._sdr is None:
              self._sdr = sdr.SDR(self, self._sdrcachedir)
          return self._sdr